Using natural rock for underpinning - opinions and options?

[nicholaseb]

I would like to have an inexpensive underpinning below our home on a post and pier foundation. I would really like to use natural rock - veneer is a bit pricey and we have no shortage of stone on our acreage. Seriously, everywhere.

Option 1 - build what is equivalent to a rock wall. My concerns are - hiding the posts.

Option 2 - use PT plywood covered in metal lath as skirting and use thin natural rock. My concerns are - the weight of the wall and finding stones that are thin enough. Thinking skirting would probably be about 18" - 24" high.

Your thoughts/opinions? Options 3-x?

[Redoverfarm]

You could use a dry stack method but there is some skill involved to avoid future failure.  Natural stone if laid requires a footing to keep it from settling and falling over.  Even if you would find thin stone to lay on the lathe depending on the size of the underpinning the weight might be a problem. 

One option is to do a parging or stucco on the lathe. You could add color to achieve the effect you desire.    Another would be to frame out and use metal roofing steel attached in the verticle fashion. A lot of roofing companies sell 2nd's and shorter cutoff pieces for a fraction of the original cost.  With either of these you do not want it to touch the ground.  Freezing and thawing will put pressure on the wall and could cause problems.  To completely seal off that you could use a crushed stone on the exterior against the material used which would allow some movement to avoid that type of failure.

[MountainDon]

If you have lots of stone, build a full perimeter rubble stone foundation. That will need a good footing (steel reinforced concrete) and when done correctly will provide a foundation that no pier and beam foundation can ever match. They look nice too.

[flyingvan]

I had the exact same desires and no shortage of stones.....Here's what I did--
  First dug a trench for a footing and formed up some pillars... (The pipe you see there was set in place to give me a good place to bend rebar in the future)
Then dry stacked stones between the pillars, being careful that every stone on the backside has something pointing towards the hillside.  Then I put a sheet of plywood behind it and dumped concrete between the drystacked stones and the plywood. 

Then formed a curb across the top out of plywood, with an open bottom.  Lined the whole form with plastic so the concrete would conform to the upper edge of all the drystacked stone


  So that's the whole stone method.

   Now for the veneer method---I bought a wetsaw on Craigslist for $50.  Best money spent on the whole project. 


 
   I don't know what kind of stone you have---this is platonic schist and VERY hard so the cutting isn't quick.  I used this for the fireplace surround and to veneer the chimney so I made a cardboard template nad my daughter puzzle fit all the pieces for me

  Then used the Mapei adhesive that you mix with water to stick it to the hardibacker.  Up the chimney I used expanded mesh like you're talking about




I went with the expanded steel on the chimney so it could be stucco/stone mix.  All stone would have been nice but it was taking way too long so this was a shortcut

[nicholaseb]

Thank you to all three of you - very helpful! Unfortunately local codes do not allow a stone foundation, which seems ridiculous given the homes that are still standing which were built on stone. I do like the stucco idea, which would be cheap and quick(or quicker). I never thought to create my own veneer out of stone - I have no idea what type of stone it is around here - can a wetsaw really cut the amount of stone I need to veneer a 20x30 cabin? I've only used them for tile, seems like it would take a super-saw to cut stone, but I have no idea.

Also, thanks for the pictures! very helpful, and your chimney looks amazing.

[flyingvan]

That's why I sent pics of the chimney----20x30 would be LOTS of veneer.  Just a standard diamond blade in a wetsaw will do it.  You could rent a big one for a weekend and just keep cutting, then do a mix of stucco/natural stone over expanded steel

[Squirl]

Unfortunately local codes do not allow a stone foundation,

That is interesting. Rubble stone (a.k.a. field stone) masonry is in the ICC and post and pier is definitely not.
http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_4_par079.htm?bu2=undefined

[Redoverfarm]

Unfortunately local codes do not allow a stone foundation, which seems ridiculous given the homes that are still standing which were built on stone.

In essence your underpinning will not be part of the foundation and will be purely asthetics and there should be no arguement with local codes.  Your piers are your foundation.

[Don_P]

That is interesting. Rubble stone (a.k.a. field stone) masonry is in the ICC and post and pier is definitely not.
http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_4_par079.htm?bu2=undefined

I agree with Squirl,
This sounds like a misunderstanding somewhere. Ask for a citation of that section... chapter and verse of the prohibition. This is one I am bringing my toys home from now, about 200 tons of fieldstone and timbers from the site.